.\"	$NetBSD: ncr.4,v 1.5 1998/03/23 10:23:30 fair Exp $
.\"
.\" Copyright (c) 1994 James A. Jegers
.\" All rights reserved.
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.Dd January 15, 1997
.Dt NCR 4
.Os NetBSD 
.Sh NAME
.Nm ncr
.Nd NCR 53C8xx SCSI driver
.Sh SYNOPSIS
.Cd "ncr* at pci? dev ? function ?"
.Cd "scsibus* at ncr?"
.Pp
.Cd "options FAILSAFE"
.Cd "options NCR_CDROM_ASYNC"
.Cd "options NCR_IOMAPPED"
.Cd "options NCR_TEKRAM_EEPROM"
.Cd "options SCSI_NCR_DFLT_TAGS=integer"
.Cd "options SCSI_NCR_MAX_SYNC=integer"
.Cd "options SCSI_NCR_MAX_WIDE=integer"
.Cd "options SCSI_NCR_SYMBIOS_COMPAT"
.Cd "options SCSI_NCR_TRUST_BIOS"
.Sh DESCRIPTION
The
.Nm
driver provides support for the NCR (Symbios) 53C810, 53C815, 53C820,
53C825, 53C860, 53C875, 53C885, 53C895, and 53C896 SCSI controller chips.
.Pp
The following kernel configuration options are available:
.Bl -ohang
.It Cd options FAILSAFE
Disables tagged command queuing and forces asynchronous transfers for
CDROM devices.
.It Cd options NCR_CDROM_ASYNC
Always use asynchronous transfers with CDROM devices.  By default,
synchronous transfers are used if the CDROM supports it.
.It Cd options NCR_IOMAPPED
Attempt to access the controller chip via I/O port-mapped I/O, falling back
to memory-mapped I/O if the I/O ports couldn't be mapped.  By default,
memory-mapped I/O is tried first.
.It Cd options NCR_TEKRAM_EEPROM
Enables support for reading the configuration EEPROM of the Tekram DC-390
series of SCSI cards.  Enable this only if using a Tekram DC-390 card.
.It Cd options SCSI_NCR_DFLT_TAGS=integer
Specifies the maximum number of tags per logical unit.  Unless
.Dv FAILSAFE
is defined, the default value is 4.  A value of 0 will disable tagged
command queuing.
.It Cd options SCSI_NCR_MAX_SYNC=integer
Specifies the maximum synchronous transfer frequency to use, in kHz.  A
value of 0 means asynchronous transfers only.  The default is 20000 (20MHz),
unless the controller chip only supports fast transfers, in which case it's
10000 (10MHz).
.It Cd options SCSI_NCR_MAX_WIDE=integer
Specifies the maximum SCSI bus width, in bytes.  Defaults to 1 on chips
that support wide SCSI, 0 otherwise.  Set this to 0 to disable wide transfers
even if both controller and device support them (e.g. when using a wide
controller and wide drive through a narrow cable).
.It Cd options SCSI_NCR_SYMBIOS_COMPAT
Enables the use of the GPIO register as a disk activity indicator.  Enable
this if the activity LED isn't working, but make sure the card doesn't
use GPIO for something else.  Cards known to support this:
ASUS SC875, Diamond FirePort 40, and Symbios SYM8751S.
.It Cd options SCSI_NCR_TRUST_BIOS
Specifies that the driver should use the register configuration set by the
firmware instead of configuring the chip itself.
.El
.Sh SEE ALSO
.Xr intro 4 ,
.Xr sd 4 ,
.Xr st 4 ,
.Xr cd 4 ,
.Xr ch 4 ,
.Xr uk 4